Technical Field
The present invention relates to a marine engine including two turbochargers and two intercoolers.
Background Art
A conventionally known configuration of an engine of a vehicle, a ship, or the like, is a configuration including two turbochargers (two-stage turbocharging system). The two-stage turbocharging system causes a turbine of one turbocharger to rotate by using an exhaust gas discharged from a cylinder, and thereby compresses air and sends the air to the cylinder side. The other turbocharger further compresses the air having been compressed by the one turbocharger, and then sends the air to the cylinder. As a result, the flow volume of air supplied to the cylinder can be increased, which leads to improvement in engine output.
Since the air compressed by the turbocharger has a high temperature, the density decreases (the mass flow rate decreases). This is why an intercooler for cooling high-temperature air is arranged after the turbocharger. Each of Patent Documents 1 to 3 discloses a two-stage turbocharging system including intercoolers (two intercoolers in total) that are arranged after one turbocharger and the other turbocharger, respectively. In the disclosures of the Patent Documents 1 to 3, an engine for use in an automobile, an engine for use in construction equipment such as a power shovel, an engine for use in an aircraft, and the like, are mentioned as objects to which the two-stage turbocharging system is applied.
Another known configuration of the two-stage turbocharging system is a configuration including two turbochargers and one intercooler, in which air having passed sequentially through the two turbochargers is cooled by the one intercooler. The two-stage turbocharging system of this type is adopted in, for example, an engine (marine engine) mounted in a ship.